diff --git a/xen/arch/Kconfig b/xen/arch/Kconfig
new file mode 100644
index 0000000000..cf0acb7e89
--- /dev/null
+++ b/xen/arch/Kconfig
@@ -0,0 +1,8 @@
+
+config NR_CPUS
+	int "Maximum number of physical CPUs"
+	range 1 4095
+	default "256" if X86
+	default "128" if ARM
+	---help---
+	  Specifies the maximum number of physical CPUs which Xen will support.
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index 2cab17b810..60e923cd46 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -31,6 +31,8 @@ config ARCH_DEFCONFIG
 
 menu "Architecture Features"
 
+source "arch/Kconfig"
+
 # Select HAS_GICV3 if GICv3 is supported
 config HAS_GICV3
 	bool
diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index d6297679bf..4781b34f78 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -25,6 +25,8 @@ config ARCH_DEFCONFIG
 
 menu "Architecture Features"
 
+source "arch/Kconfig"
+
 config BIGMEM
 	bool "big memory support"
 	default n